Objectives: We examined whether a relationship exists between the vasoconstrictive response to endogenous nitric oxide (NO) synthesis inhibition and the severity of heart failure in patients with congestive heart failure (CHF).
Background: Controversy exists as to whether the vasoconstrictive response to NO synthesis inhibition in patients with CHF is comparable to that in normal subjects or is enhanced.
Methods: Forearm blood flow (FBF) and calculated forearm vascular conductance (FVC) were obtained using plethysmography before and after administration of the NO synthesis inhibitor L-NMMA (NG-monomethyl-L-arginine) in 40 patients with CHF due to dilated cardiomyopathy and in 16 normal control subjects. Basal plasma B-type natriuretic peptide (BNP) and nitric oxide concentrations were measured in all subjects.
Results: Plasma BNP and nitrite/nitrate (NOx) levels in the patients group were significantly greater and baseline FBF was significantly less. Administration of L-NMMA significantly decreased FBF and FVC in both groups. The percent changes in FBF (%FBF) and FVC (%FVC) from the baseline after L-NMMA correlated significantly with plasma BNP level (%FBF: r = 0.72; %FVC: r = 0.76; both p < 0.001). Percent changes in both FBF and FVC were greater in patients with BNP > or = 100 pg/ml than in normal subjects; however, in patients with BNP < 100 pg/ml they were comparable to those in normal subjects.
Conclusions: Vasoconstrictive response to L-NMMA in patients with CHF was preserved or enhanced in proportion to the basal plasma BNP level, indicating a close relationship between the contribution of endogenous NO to basal vasomotor tone and the severity of heart failure.